IDH1 and central nervous system cancer: Most MRS sequences have targeted the C4 proton resonances at ~2.25 ppm by optimizing point-resolved spectroscopy (PRESS) techniques.19–23 Single-voxel MRS PRESS with TE = 97 ms with a larger voxel (2 × 2 x 2 cm3) has shown greater accuracy compared to TE = 30 ms.24 A subsequent study established quantitative evaluation of 2HG in IDH-mutant gliomas by MRS to be both reproducible and to reliably reflect the clinical change in disease from an indolent stage through post-treatment.